In press-and-blow glassware forming machines, a molten glass gob is fed into a blank mold and a plunger is moved into the blank mold to form the molten glass against the confines of the blank mold cavity. The glass blank or parison formed in the blank mold is then transferred to a blow mold for further processing. At the blank mold stage, the plunger, or the plungers in a multiple-cavity forming machine, are carried by a plunger foot assembly for adjusting plunger height to accommodate blank molds of differing sizes and/or for retracting the plunger(s) for maintenance or repair. A general object of the present disclosure is to provide an improved plunger foot assembly.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A plunger foot assembly in accordance with one aspect of the present disclosure includes a preassembled gearbox for mounting on a section box base plate of a glassware forming machine. The preassembled gearbox has an input and an output gear with an internally threaded central opening. A hollow externally threaded shaft is threadably coupled to and extends from the internally threaded opening of the output gear. A plunger support is mounted on the hollow externally threaded shaft such that rotation of the output gear of the gearbox raises and lowers the plunger support. The plunger support has an upper face for mounting at least one plunger with air ports of the plunger opening at the face of the support. The plunger support also has air passages for feeding plunger up, plunger down and plunger cooling air to the air ports of a plunger mounted on the plunger support, and a cooling air exhaust passage for feeding cooling air exhausted from the plunger mounted on the support to the hollow interior of the externally threaded shaft. At least one telescoping tube assembly has a base for mounting on the section box base plate, and telescoping tubes with inlet ports for receiving plunger up, plunger down and plunger cooling air and outlets coupled to the air passages in the plunger support.